/Engine/Plugins/Experimental/PlatformCrypto/Source/PlatformCryptoTypes/Public/PlatformCryptoTypes.h
For ciphers that require authentication tags, you must call this function to set the AuthTag for the encrypted data before you may call Finalize.
[EPlatformCryptoResult](API\Plugins\PlatformCryptoTypes\EPlatformCryptoResult) SetAuthTag ( const [TArrayView](API\Runtime\Core\Containers\TArrayView)< const uint8 > AuthTag )